EXPLOSION AT THE TWIN TOWERS: Fire Safety; Tougher Code May Not Have Helped

By JOSH BARBANEL

Published: February 27, 1993

Fire experts said the force of the explosion yesterday at the World Trade Center, which ripped doors off elevators, knocked out power and sent thick smoke up stairwells, would have disabled even the most sophisticated fire system.

And while the building is exempt from New York City's stringent fire codes, these experts said even the most exacting high-rise safety rules would have made little difference in the death toll, injuries or damage.

But they said a study of yesterday's disaster could lead to further improvements in fire safety. 'Knock Everything Out'

"A terrorist bomb, or whatever it was, was planted in exactly the right place to knock everything out," said Elmer Chapman, a retired New York City deputy fire chief and an expert on high-rise fires. "All of this is going to require a lot of analysis and retrofitting of many buildings."

To Amy Herz Juviler, a former Criminal Court judge, the image of smoke snaking down the emergency stairwells of the World Trade Center yesterday recalled safety concerns raised two decades ago about the flagship project of the Port Authority of New York and New Jersey.

Back then the building was caught in a jurisdictional tug-of-war between the Port Authority and the Fire Department, which wanted to impose the city's stringent high-rise fire-safety rules.

In the early 1970's Ms. Juviler, then an assistant attorney general who had just moved into the state's newly finished offices on the 47th floor of 2 World Trade Center, was startled to see smoke from small construction fires in the basement curl up through the emergency stairwells for at least 50 stories and she was worried.

"I called the Fire Department at the request of the Attorney General, and the Fire Department assured me that this was not the world's safest building," she recalled yesterday. "Those stairwells, not some but all of them, were flues. There was no break to keep the smoke out."

Almost from the day in 1970 when a propane gas explosion shook the steel skeleton of the skyscraper, through dozens of fires, large and small, fire safety at the World Trade Center has been in dispute. High Standards

Asked about the safety of the World Trade Center, Eugene Fasulloa, the Port Authority's chief engineer, said, "The twin towers were built to the highest standards."

But Ms. Juviler and state legislators who fought for years to put the Trade Center and other Port Authority structures under the New York City code remain concerned that some of the mishaps and mayhem could have been avoided.

The picture painted by the Fire Department was so bleak, Ms. Juviler said, that the issue was dropped. "We chose not to further alarm our people," she said. "In the case of a real fire like 'The Towering Inferno' we knew there was no escape."

Under a compact passed by the New York State Legislature in 1962, the construction of the World Trade Center and other projects were within the "sole discretion" of the bistate port agency and were specifically exempted from the "local laws, resolutions, ordinances, rules and regulations of the City of New York." Suck Smoke Out

The twin towers rely on heating, ventilation and air-conditioning equipment to suck out smoke and pump in fresh air in the event of a fire, a system that is most useful for small, contained fires. The system failed almost immediately, fire officials said, when the blast blew out power in the building.

For years John O'Hagan, a former New York City Fire Commissioner, pressed for the installation of a sprinkler system, or a pressurization system on the stairways, which puts extra air pressure on emergency stairwells to push smoke out and limit injuries from smoke inhalation. Such systems are required under a city code adopted in the early 1970's.

When a three-alarm fire in the World Trade Center spread to three floors in 1975 and caused extensive damage, Mr. O'Hagan contended the absence of sprinklers played a role. He then used the occasion to press for the installation of sprinklers.

In 1976, Port Authority officials agreed to spend $14 million for sprinklers. Five years later, they announced a new $45 million plan to install sprinklers, and fire experts said the job was completed in the last five years or so. Open conduits for telephone lines were also made fire-safe.

Mr. Chapman, the retired deputy fire chief, said the pressurized stairwells could in theory have made a difference. But he said that there was no requirement in the New York City code or elsewhere to install auxiliary generators to power the pressurization equipment.

For years some legislators pressed for a new rule that would force the Port Authority to comply with New York City fire codes. But the measure never passed the New York State Legislature, or the New Jersey Legislature. AT A GLANCE: How Smoke Can Fill a Tower

Several factors affect the spread of smoke throughout a building's floors, stairwells and elevator shafts. Among them are hot air rising from a fire, external wind (which decreases air pressure outside) and the ventilation system. Smoke can travel through fire escape routes if doors are not kept closed. The Stack Effect In a tall building, the flow of smoke is determined by differences in temperature inside and outside in what is known as the stack effect. When the temperature inside is greater that outside, air is drawn in through doors and windows at lower levels and expelled at higher levels. At the bottom of the building, air pressure is greater outside than inside, but pressure is greater inside at the top. At a point determined by the height of the building and the outside weather, there is a neutral plane where pressure inside and outside are equal. Below the neutral plane smoke tends to flow inward and upward as it does in a chimney or smokestack. Above the plane smoke spreads out from the center. The stack effect can cause upper floors to be filled with smoke very quickly. (Source: "An Introduction to Fire Dynamics" by Dougal Drysdale)

Photos: The central location of yesterday's explosion below the World Trade Center forced smoke up stairwells for at least 50 floors. People evacuating the complex encountered smoke in the lobby of 1 World Trade Center. (Marilynn K. Yee/The New York Times); Police officers helping an injured woman away from the scene. (Associated Press)